1. Field of the Invention
The present invention relates to a conductive tab and a battery pack having the same, and more specifically to a conductive tab capable of being exactly welded at a predetermined position of a secondary batter and being not closely welded to each other and a battery pack having the same.
2. Description of the Related Art
Generally, only one secondary battery is not enough as a power source to a notebook PC, a personal portable terminal and the like. Accordingly, a power supply apparatus used in such a notebook PC or the like is in the form of a plurality of secondary batteries connected in series or in parallel so as to obtain desirable voltage and electric capacity. Herein, a configuration, in which a protective circuit module is electrically connected to the plurality of secondary batteries and then is received in a case, is the so-called battery pack.
A conductive tab is usually used as a member to connect a plurality of secondary batteries in series or in parallel as mentioned above. For example, such a conductive tab is comprises of a battery connecting part in a rectangular plate type and a wire connecting part bent from the battery connecting part. The battery connecting part of the conductive tap is welded to all the same electrodes such as positive electrodes or negative electrodes, so that a plurality of secondary batteries is connected in parallel. Also, the battery connecting part of the conductive tap is welded to the opposite polarity of the secondary batteries, so that a plurality of secondary batteries is connected in series. In addition, the wire connecting part of the conductive tab is bent in a perpendicular direction to the battery connecting part, and then on the surface thereof, a power wire for drawing out power or a sensing wire for sensing voltage is soldered.
In the welding process, a plurality of secondary batteries is aligned and then a conductive tap in a plate type is temporarily contacted with one side portion thereof. After that, the conductive tab is welded electrically and mechanically to the secondary batteries by a resistance welding or a laser welding method.
However, in the welding process, the position of the conductive tab is easily changed in the secondary batteries. In other words, the position of the conductive tab may be changed while the conductive tab temporarily contacts to the secondary batteries before the welding process and/or by a contact with a welding rod during the welding process. Therefore, the different positions of the conductive tab to contact secondary batteries make it difficult to solder the power wire or sensing wire later. In some cases, a short circuit with an unwanted area may be incurred.
Meanwhile, conventional conductive tabs are kept in laminated state. However, the conductive tabs that are laminated and kept sometimes strongly adhere to each other by oil used for blanking during the manufacturing process of the conductive tabs or by moisture remained after a washing process. Therefore, it is frequent that a plurality of conductive tabs closely adheres to each other and is welded to secondary batteries as their states are. In addition, since such conductive tabs are very thin, it is difficult for a worker or working equipment to notice whether the plurality of conductive tabs are closely adhered to each other, thus it often causes a defective welding and soldering. In other words, a battery connecting part of each conductive tab should be welded to secondary batteries, and a wire should be soldered to a wire connecting part thereof. However, when several conductive tabs closely adhere together and are welded, the welding conductive tabs and the secondary batteries cannot be strongly welded due to the resistance. Beside, if the conductive tabs welded in this state are soldered, electrical connection strength between the wire and the secondary battery is naturally weaken.